Paleotemperature Analysis of Caribbean Cores P6304-8 and P6304-9 and a Generalized Temperature Curve for the past 425,000 Years

Abstract

Different techniques for preparing organic carbonates for mass spectrometric analysis may give slightly different results depending upon the material used and the grain size to which it is reduced. Two deep-sea cores from the central Caribbean have been analyzed. The samples from one core have been treated with vacuum roasting, and the samples from the other core have not been roasted. The two sets of results are similar and differ 0.5‰ from samples that have been ground to powder and roasted in a stream of helium. When using pelagic Foraminifera, no roasting and vacuum roasting appear to yield isotopic results slightly closer to the true temperature than the results obtained with helium roasting. The two cores analyzed and others previously described are correlated by means of several different criteria. This correlation yields a generalized temperature curve which extends from the present to 425,000 years ago. The high (.997), direct correlation observed between the stratigraphic positions of the isotopic temperature minima in deep-sea cores and the ages of the Milankovitch insolation minima at 65° N. provides strong support for theories of glaciation based on the "Milankovitch mechanism" and indicates that the over-all oceanic rate of sedimentation, if averaged across one or more temperature stages, remained essentially constant during the past several hundred thousand years.